Consider a piece of silicon (X) doped with both donor and acceptor imp...
Explanation:
Semiconductors: Semiconductors are materials that have a conductivity between conductors (metals) and nonconductors (insulators). They can be used to make electronic devices such as diodes, transistors, and integrated circuits.
Doping: Doping is the process of intentionally introducing impurities into a semiconductor to change its electrical properties. Impurities can be either donor or acceptor atoms.
Donor Impurities: Donor impurities are atoms that have one more valence electron than the semiconductor atoms. When a donor impurity is introduced into a semiconductor, it donates its extra electron to the conduction band of the semiconductor, creating a free electron.
Acceptor Impurities: Acceptor impurities are atoms that have one less valence electron than the semiconductor atoms. When an acceptor impurity is introduced into a semiconductor, it creates a "hole" in the valence band of the semiconductor, which behaves like a positive charge carrier.
Complete Ionization: Complete ionization means that all of the donor and acceptor impurities have either donated or accepted an electron, leaving no charged impurities.
Sample X: Sample X is doped with both donor and acceptor impurities. The donor impurities will create free electrons, while the acceptor impurities will create holes. The electron concentration will depend on which impurity type is more dominant.
The total impurity concentration in sample X is:
N = ND + NA = 2 x 10^17 + 10^17 = 3 x 10^17/cm^3
If we assume complete ionization, then the donor impurities will donate all of their extra electrons to the conduction band, creating free electrons. The acceptor impurities will accept all of these electrons, creating holes in the valence band.
The electron concentration in sample X is:
n = ND = 2 x 10^17/cm^3
The hole concentration in sample X is:
p = NA = 10^17/cm^3
Sample Y: Sample Y is doped with only donor impurities. The donor impurities will create free electrons, and if we assume complete ionization, all of these impurities will donate their extra electrons to the conduction band, creating free electrons.
The electron concentration in sample Y is:
n = ND = 10^17/cm^3
Conclusion: The electron concentration in sample X is greater than the electron concentration in sample Y, but this is because sample X is doped with more impurities. If we compare the concentration of free electrons created by the donor impurities in both samples, then sample Y has a higher concentration of free electrons.
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